Albert schmidt



A. SCHMIDT.

SPARK PLUG.

APPLICATION FILED JAN. 8. I916.

Patented July 8, 1919.

awuowtoz 2,506 $072722 2 it UNITED STATES PATENT OFFICE.

ALBERT SCHMIDT, OF FLINT, MICHIGAN, ASSIGNOR TO CHAMPION IGNITION COMPANY, OF FLINT, MICHIGAN, A CORPORATION OF MICHIGAN.

SPARK-PLUG.

Specification of Letters Patent.

Patented July 8, 1919.

To all whom it may concern:

Be it known that I, ALBERT SCHMIDT, a citizen of the Republic of France, residing at Flint, in the county of Genesee and State of Michigan, have invented certain new and useful Improvements in Spark-Plugs, of which the following is a specification, reference being had therein to the accompanying drawings.

The invention relates to spark plugs particularly designed for use in connection with high-speed explosion engines, and it is the object of the invention to overcome certain defects in constructions heretofore employed, as hereinafter set forth. 1

In the drawings:

Figure 1 is a longitudinal section through my improved construction of plug; Fig. 2 is a perspective view of the electrode with the inner insulator thereon; and

Fig. 3 is a perspective view of the outer insulator.

In the construction of spark plugs it is equally essential to maintain a gas-tight seal and electrical insulation. Many substances that are good insulators at low temperatures lose to a large extent their insulating property at a higher temperature. Also there are materials which are good insulators at high temperatures but which are not adapted for the formation of a gas-tight seal. In particular porcelain which at low temperatures is highly dielectric loses this characteristic at a temperature often attained when used on high-speed engines. Mica will maintain its insulating properties at the higher temperatures, but as heretofore constructed plugs having insulators of this material are not gas tight.

The present invention overcomes this diiliculty by a construction in which the portion of the insulator exposed to high heat is formed of mica or other material which will safely stand this temperature, while on the other hand the portion of the insulator which forms the gas seal is constructed of a material such as porcelain which is impervious to gas. As shown, A is the metallic casing of a spark plug of any suitable construction, B is the insulated electrode wh1c h passes centrally through said casing and is provided with a metallic head C; at its inner end, G is an insulator of the high-heat resistin material which extends from the head to a point within the metallic casing where the temperature is maintained lower, and E is an insulator formed of porcelain or other gas-tight material which abuts against the inner end of the insulator D and forms a gas-tight seal with the metallic casing A and the electrode B.

The insulator section G may be of any suitable construction such as a wrapping F of mica around the shank of the electrode B and a series of circular disks G sleeved upon said wrapped shank, the outer end of the series abutting against the head C and the inner end against the face of the insulator E. The insulator E is sealed within the casing A by any suitable means, such as by bearing with its inner end against the gasket H upon a shoulder I of the casing, and by having a flange J on the casing engagin an outer shoulder K on the insulator. uch a construction will form a tight seal between the insulator and the outer casing, but there is still a chance forleakage between the mica disks and around the shank of the electrode. To guard against this a gas-tight seal is formed between the outer end of the electrode shank and the end of the insulator E by suitable means such as a threaded collar L engaging a threaded portion of the shank and clamping against agasket M bearing upon the end of the insulator.

With the construction as described 1n use,

the metallic casing A being in contact with.

the water-cooled jacket of the engine is maintained at a comparatively low temperature, and the insulator E which is clamped in contact with said casing will be cooled by thermal conduction. Thus the insulating property of the member E. is maintained which will prevent leakage of current from the electrode passing therethrough. On the other "hand, the'insulator G which is exposed to the high temperature will maintain its insulating properties so as to avoid leakage of the current therethrough. This insulator also assists in dissipating the heat from the exposed end of the electrode, which is conducted therethrough into the cooled insulator E.

What I claim as my invention is:

1. A spark lug, comprising an outer casing and insu ated electrode passing therethrough, an insulator for the inner end of said electrode formed of a mica wrapping about the electrode shank, a series of mica disks sleeved upon.- said wrapping and shank,

a head onsaid electrode bearing against the inner end of the series of disks, an insulator of a gas-proof material bearing against the inner end of said series of disks and extending outward through said casing, means for forming a gas seal between said casing and the latter insulator, and a clamping collar on the outer end of said electrode forming a sealing engagement with said outer insulator and constituting a means of clamping said series of disks.

A spark plug, comprising, an outer casing, an insulated electrode passing therethrough, an insulator for the inner end of said electrode formed of a mica wrapping about the electrode shank, a series of mica disks sleeved upon said wrapping shank, an insulator of a gas proof material bearing against the inner end of said series of disks and extending outward through said casing, said casing having opposed portions for clamping said latter insulator therein, means for forming a gas seal between said casing and the latter insulator and means for forming a gas seal between said electrode 25 and outer insulator and for clamping said series of dlsks.

In testimony whereof I affix my signature.

ALBERT SCHMIDT. 

